From: Bart Van Assche <Bart.VanAssche@sandisk.com>
To: "axboe@fb.com" <axboe@fb.com>,
"ming.lei@redhat.com" <ming.lei@redhat.com>
Cc: "hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"jthumshirn@suse.de" <jthumshirn@suse.de>,
"jth@kernel.org" <jth@kernel.org>
Subject: Re: [PATCH] block: fix bio_will_gap()
Date: Thu, 13 Apr 2017 16:22:22 +0000 [thread overview]
Message-ID: <1492100540.5176.6.camel@sandisk.com> (raw)
In-Reply-To: <20170413160626.14635-1-ming.lei@redhat.com>
On Fri, 2017-04-14 at 00:06 +0800, Ming Lei wrote:
> But if one rq starts with non-aligned buffer(the 1st bvec's
> bv_offset isn't zero) and if we allow to merge, it is quite
> difficult to respect sg gap limit, especially the segment
> can't be at maximum segment size, otherwise the segment
> ends in unaligned virt boundary. This patch trys to avoid the
> issue by not allowing to merge if the req starts with non-aligned
> buffer.
Hello Ming,
Why is it considered difficult to detect whether or not a gap exists if
the offset of the first bio is non-zero? Please note that a thoroughly
tested version of gap detection code that supports non-zero offsets for
the first element is already upstream. See also ib_map_mr_sg() and
ib_sg_to_pages() in drivers/infiniband/core/verbs.c.
Thanks,
Bart.=
next prev parent reply other threads:[~2017-04-13 16:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 16:06 [PATCH] block: fix bio_will_gap() Ming Lei
2017-04-13 16:22 ` Bart Van Assche [this message]
2017-04-14 2:04 ` Ming Lei
2017-04-14 11:26 ` Johannes Thumshirn
2017-04-14 19:51 ` Jens Axboe
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